Bike frame

Abstract

A bike frame includes including a seat tube (10) for receiving a seatpost (2), a front portion comprising a top tube (13) connecting the seat tube (10) to a head tube (16), the seat tube (10), the top tube (13). The head tube (16) extends in a plane of symmetry of the bike frame (1). A rear portion has two chain stays (11a, 11b) and two seat stays (12a, 12b) arranged symmetrically relative to the plane of symmetry of the bike frame (1). The two seat stays (12a, 12b) are independent of each other and the two seat stays (12a, 12b) have a preform that is curved along at least one arc in a plane passing through the two seat stays, so as to enable the two seat stays to move away from or closer to each other under the action of a vertical load.

The invention claimed is: 
     
       1. A bike frame comprising:
 a seat tube configured to receive a seatpost, 
 a front portion comprising a top tube connecting the seat tube to a head tube, said seat tube, said top tube and said head tube extending in a plane of symmetry of the bike frame, and 
 a rear portion comprising two chain stays and two seat stays arranged symmetrically relative to the plane of symmetry of the bike frame, 
 wherein each seat stay has a perpendicular cross-sectional profile that is elongated in a direction parallel to the plane of symmetry, in that the two seat stays are independent of each other and in that the two seat stays have a preform that is curved along at least one arc in a plane passing through the two seat stays, so as to enable the two seat stays to move away from or closer to each other under the action of a vertical load. 
 
     
     
       2. The bike frame according to  claim 1 , wherein the preform is curved towards the outside of the bike frame. 
     
     
       3. The bike frame according to  claim 1 , wherein the preform is curved towards the inside of the bike frame. 
     
     
       4. The bike frame according to  claim 1 , wherein the preform includes a series of arcs alternately curved towards the inside and then towards the outside of the bike frame. 
     
     
       5. The bike frame according to  claim 1 , wherein the two seat stays are each connected to a front lateral half of the seat tube. 
     
     
       6. The bike frame according to  claim 1 , wherein the two seat stays are each connected to the top end of the seat tube. 
     
     
       7. The bike frame according to  claim 1 , wherein said bike frame also includes a fastening lug for a rim brake that extends in the plane of symmetry of the frame, from the seat tube towards the rear portion. 
     
     
       8. The bike frame according to  claim 1 , wherein said bike frame also includes a fastening element rigidly connected to a bottom bracket of said bike frame to support a rim brake under the two chain stays. 
     
     
       9. The bike frame according to  claim 1 , wherein said bike frame also includes a supporting element provided at the end of each seat stay at the joints with the chain stays to support a rear disc brake.